A dehumidifier 1 comprising a rotatably and drivably mounted disk-shaped dehumidification rotor, as shown in FIG. 6, for example, is known (e.g., U.S. Pat. No. 6,083,304). The dehumidifier 1 comprises a passage for dehumidification X through which air to be dehumidification is introduced into the dehumidifier 1 from outside by a dehumidification fan 3 so as to dehumidify the air by passing through a dehumidification rotor 2, and through which the dehumidified air is discharged to outside; and a passage for regeneration Y through which air for regeneration for regenerating the dehumidification rotor 2 is circulated in the dehumidifier 1.
This passage for regeneration Y comprises a regeneration fan 4 for circulating the air for regeneration in a closed circuit, a heater 5 for heating the air for regeneration before passing through the dehumidification rotor 2, and a heat exchanger for cooling 6 which cools the air for regeneration after passing through the dehumidification rotor 2. The passage for regeneration Y further comprises a heat exchanger for recovering heat 7 for raising the temperature of the air for regeneration before passing through the dehumidification rotor 2 utilizing the temperature of the air for regeneration after passing through the dehumidification rotor 2. By virtue of the heat exchanger for recovering heat 7, the temperature of the air for regeneration before passing the heater 5 is raised so as to decrease the power consumption of the heater 5, thereby saving energy.
The dehumidification rotor 2 is harbored in a rotor case 31, and is rotated at a very slow rotation speed of, for example, once per 3 minutes, for example. In the rotor case 31, an opening for dehumidification 38 which is so formed as to expose a region of the dehumidification rotor 2, which region is so defined as to have a prescribed central angle in the dehumidification rotor 2, and an opening for regeneration 39 located in the passage for regeneration which is so formed as to expose a region of the dehumidification rotor, which is located in an area other than the first-mentioned region having the prescribed central angle, are formed, through which openings the air to be dehumidified and the air for regeneration for regenerating the dehumidification rotor 2 pass, respectively.
The air to be dehumidified inhaled into the dehumidifier 1 through the passage for regeneration X is made to pass through the opening for dehumidification 38, during which the moisture in the air is adsorbed by the dehumidification rotor 2, thereby being dehumidified, and then discharged to outside. On the other hand, the region of the dehumidification rotor 2, which adsorbed the moisture, enters the opening for regeneration 39 from the opening for dehumidification 38, thereby being regenerated by the air for regeneration and exhaling the adsorbed moisture. The moisture exhaled from the dehumidification rotor 2, in the form of vapor, flows in the passage for regeneration, cooled by the heat exchanger for cooling so as to be condensed, and the thus formed condensed water drops onto a drain pan and is collected in a reservoir tank 26.
Although the directions of the air to be dehumidified and of the air for regeneration, passing through the dehumidification rotor, are opposite in the mode shown in FIG. 6, a mode in which these directions are the same, as shown in FIG. 7, is also known. Although the principle of dehumidification and the operation of the mode shown in FIG. 7 are the same as those of the mode shown in FIG. 6, the difference in pressure between the entrance of the region for dehumidification (the region in the dehumidification rotor, through which the air to be dehumidified passes) and the entrance of the region for regeneration (the region in the dehumidification rotor, through which the air for regeneration passes), as well as the difference in pressure between the exit of the region for dehumidification and the exit of the region for regeneration, can be made smaller than in the mode shown in FIG. 6 in which the directions of the air to be dehumidified and the air for regeneration are opposite, so that it is preferred.
With the conventional dehumidifiers (FIGS. 6 and 7) having the above-described constitutions, at a time point, the anterior area in the dehumidification rotor 2, located anterior in the direction of rotation of the dehumidification rotor 2, has dwelled for a longer time in the opening for regeneration 39 than the posterior area in the dehumidification rotor 2, located posterior in the direction of rotation of the dehumidification rotor 2, so that the anterior area has been exposed to the heated air for regeneration for a longer time. Therefore, the air for regeneration after passing through the anterior area is hotter than the air for regeneration after passing through the posterior area.